Get the 6400+ BE if your a gamer, because most games don't require any extra cores (known to hit 3.4Ghz+ quite often).

Get the 9600 BE if you do a lot of video editing, photoshop, file compressing, etc... (The extra cores have been proved to be really effective for these applications).

If you want to settle for something in between, get the Phenom 9500. It tops out at around 2.5Ghz with the current chips and BIOS versions, which isn't too bad. With a lower cost than the 9600 BE, and two more cores than the 6400+ BE; you have a killer chip. You can pick one of these up for $230.00 on NCIX.